Dicarbonyl compounds may include dicarboxylic acids, organic compounds that contain two carboxylic acid (—COOH) functional groups, and diesters, organic compounds that contain two ester functionalities (—COOR, where R may be an alkyl group or other organic moiety). Dicarbonyl compounds may be straight chain, branched chain, or aromatic, and are suitable substrates for preparing organic constituents for the pharmaceutical and food industries. For example, dicarboxylic acids are useful materials for preparing fragrances, polyamides, adhesives, lubricants, polyesters, and other commercially valuable products.
Adipic acid, as an example dicarboxylic acid, is a commodity chemical with global production on the order of 2.5 million metric tons, annually, and the primary commercial use of adipic acid is as a monomer in the manufacture of Nylon 6,6. Nylon 6,6 is a polyamide of the diamine hexamethylenediamine (IUPAC name: hexane-1,6-diamine) and the dicarboxylic acid adipic acid (IUPAC name: hexanedioic acid) and may be produced by the polycondensation of the diamine and the dicarboxylic acid. Types of nylons, such as Nylon 6,6, are distinguished by a numerical suffix that specifies the numbers of carbons donated by the monomers, with the number of carbons from the diamine monomer listed first, followed by the number of carbons from the dicarboxylic acid monomer. Other nylons that may be formed from dicarboxylic acids may include Nylon 6,9, Nylon 6,12, and Nylon 4,6.
Adipic acid and esters thereof (adipates), as well as other dicarboxylic acids and diesters, are often produced from the petrochemically derived raw materials benzene or butadiene. Efforts to replace these petrochemically derived raw materials are ongoing, and there remains a need to provide alternative scalable and cost effective approaches for commercially producing diesters and dicarboxylic acids using alternative carbon sources.